Field of the Invention
The present invention relates to a technology of inspecting an insulating film formed in an inspection sample mainly made of a semiconductor material.
Description of the Background Art
The insulating film (passivation film) is formed on a surface of a semiconductor wafer in order to prevent degradation. In a solar cell, the insulating film (passivation film) is formed in order to provide high conversion efficiency.
C-V (Capacitance-Voltage) measurement is widely performed as a method for evaluating the insulating film formed on the semiconductor wafer. In the C-V measurement, an electrode disc of aluminum is deposited on the insulating film of the semiconductor wafer, and a probe pin is brought into contact with the electrode disc, thereby applying voltage to the semiconductor wafer. A change in electric capacity (capacitance) corresponding to the voltage is measured by changing the voltage.
For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2013-38340) discloses a technology associated with the C-V measurement of the semiconductor wafer.
In the C-V measurement, complicated work is problematic. That is, for the C-V measurement, it is necessary to bring the probe pin into contact in each electrode disc to measure the electric capacity, which results in the problematic measurement work.
Additionally, for C-V measurement, resolution is hard to be improved. That is, in the C-V measurement, compactness and a small forming interval of the electrode disc deposited on the surface of the insulating film are required to improve the resolution. However, the resolution is hard to be improved from the viewpoint of workability degradation and cost.